282 BULLETIN 188, UNITED STATES NATIONAL MUSEUM 



distinct from Gyrinocheilus from the information now available. 

 Fowler distinguished the genera as follows : 



Predorsal scales small ; scales on caudal base small ; eye well postmedian or near 

 last third in bead ; 2 rows of large, dark, alternating or opposed spots along 

 side of body Gyrinocheilus 



Predorsal scales very small and crowded ; scales on caudal base large ; eye slightly 

 postmedian in head ; 2 rows of large dark spots only partly or not at all alter- 

 nating along side of body Gyrinocheilops 



The opinion is held that the differences here indicated, insofar as they 

 are constant, have only specific, not generic, significance, and that 

 GyHnocheilops (type pennocki from the Mekong) is a synonym of 

 Gyrinocheilus (type 'pustulosus from Borneo). 



Genus GYRINOCHEILUS Vaillant 



Gyrinocheilus Vaillant, Notes Leyden Mus., vol. 24, p. 107, 1902. (Type, Oyrino- 

 cheilus pustulosus "Vaillant.) 



This outstanding genus may at once be recognized by the absence 

 of a rostral fold, the ventral surface of the snout being continued as 

 the upper lip ; by the close union of the upper and lower lips on each 

 side into a coil occupying the postlabial groove ; by the rasplike folds 

 of the inner surface of the lips; by the fleshy prolongation of the 

 isthmus into the postlabial groove immediately behind the lower lip ; 

 by the absence of pharyngeal teeth; and by the existence, above the 

 regular branchial opening, of a supplementary opening which has 

 an inhalent function. 



The first fish referable to this genus seems to have been described 

 by Tirant in 1883, but as it was placed in the genus PsilorhynchKS 

 and the description and figures were faulty, the status of the species 

 remained uncertain until Hora (1935) recognized its true relations. 

 In the meantime, Vaillant (1902) described Gyrinocheilus pustulosus 

 as a new genus and new species from Borneo; and Berg (1906) de- 

 scribed G. kaznakovi from a part of Southeastern Thailand now in 

 Cambodia, this form being apparently referable to Tirant's Psilo- 

 rhynchus aymonieri. More recently another species, G, pennocki^ has 

 been described by Fowler (1937) from the Mekong, where it forms 

 the boundary between Eastern Thailand and Cambodia. 



Two so-called new species of Gynnocheilus {G. roulei and G. pel- 

 legrini) described from Szechwan, western China, by Tchang cannot 

 possibly represent this genus, and their possession of a single branchial 

 aperture excludes them from this family. 



la. Branched dorsal rays 9; eye in adult well behind midlength of head. 



aymonieri 

 1&. Branched dorsal rays 10 ; eye in adult nearly in midlength of head pennocki 



